In our laboratory, we are using the process of ovarian development to delineate hormone-triggered programs of differentiation at the cellular and molecular levels. Under the tenure of this grant, we plan to use recombinant DNA technology to isolate, localize, characterize and sequence the vitellogenin structural genes of D. melanogaster and D. grimshawi. We will use the genes to study the interactions between the process of vitello-genesis and the aging of the flies. By a combination of biological, biochemical, immunochemical, and electron microscopical methods of analysis, we will determine the nature of the interactions, and the level at which these operate. Several female-sterile mutant strains will be screened to identify age-dependent mutants, and also those which are deficient for vitellogenin synthesis or which synthesize modified vitellogenin proteins. These latter ones will be used for studying the regulation of vitellogenin gene expression. Having established what kind of interactions exist between vitellogenesis and aging of the flies, we will attempt to alter the effects via ovarian transplantations and hormonal applications.